An accelerated approach to tissue expansion for breast reconstruction: experience with intraoperative and rapid postoperative expansion in 370 reconstructions

Breast reconstruction with tissue expansion is a well-established technique that offers satisfactory aesthetic results with minimal patient morbidity. The traditional period of expansion, however, continues to be a significant source of patient inconvenience and dissatisfaction. The objective of this study was to develop and evaluate a protocol for rapid tissue expansion. A total of 370 breast reconstructions in 314 patients who underwent rapid tissue expansion were retrospectively reviewed. Contraindications to rapid expansion were considered to be previous radiation, mastectomy skin flaps of questionable viability, and an excessively tight skin envelope. All expanders were placed submuscularly and filled to 40 to 50 percent of tissue expander volume. Office expansion was undertaken within 10 to 14 days after the operation and continued on a weekly basis. Each expansion was limited by patient tolerance up to a maximal pressure of 40 mm of water or a volume of 120 cm3. Expansion was considered complete once the expanded breast was 30 to 50 percent larger than the contralateral breast. If required, postoperative chemotherapy was given during the expansion period. Mean patient age was 48 years (range, 23 to 73 years). Two hundred fifty-eight patients had unilateral reconstructions. Three hundred two patients had immediate reconstruction. Mean tissue expander size was 583 cm3 (SD, 108 cm3). Mean intraoperative expansion was 271 cm3, or 46 percent (SD, 9 percent) of the tissue expander size. The first expansion was started 12 days (SD, 3 days) after the operation. The mean volume of each expansion was 88 cm3 (SD, 23 cm3). Expansion was completed in 4.7 office visits (SD, one visit). Mean final expander volume was 672 cm3 (SD, 144 cm3). The expanders were overexpanded by 15.3 percent (SD, 8.4 percent). The mean time between expander placement and the final expansion was 6.6 weeks (SD, 3 weeks). The overall complication rate was 4 percent. Ten patients developed cellulitis, five patients had hematomas requiring drainage, and one expander became exposed. A total of eight expanders were removed: four for cellulitis, one for a hematoma, one because of locally recurrent disease, one because of expander exposure, and one at the patient's request for no medical reason. Intraoperative and rapid postoperative tissue expansion is a safe and reliable technique that offers a significant improvement over conventional techniques. In this accelerated protocol, expansion may be completed in less than 7 weeks. The result is decreased patient morbidity and delays in adjuvant therapy at no detriment to the final surgical outcome.     

The premature removal of tissue expanders in breast reconstruction.

The role of tissue expanders in breast reconstruction is well established. Little information exists, however, regarding the incidence and etiology of premature removal of the tissue expander before planned exchange to a permanent breast implant. The purpose of this study was to review our 10-year experience with tissue expander breast reconstruction and identify factors relating to the premature removal of the tissue expander. This study is a retrospective review of 770 consecutive patients who underwent breast reconstruction with tissue expanders over the past 10 years. Breast reconstruction was immediate in 90 percent of patients. Patients were expanded weekly, and adjuvant chemotherapy was begun during the expansion process when required. Factors potentially affecting premature expander removal (chemotherapy, diabetes, obesity, radiation therapy, and smoking) were evaluated. Fourteen patients (1.8 percent) with a mean age of 47 years (range, 38 to 62 years) required premature removal of their tissue expander. Expanders were removed a mean of 3.2 months (0.1 to 8 months) after insertion. Causes for premature removal of the tissue expander included infection (7 patients), exposure (2), skin necrosis (2), patient dissatisfaction (2), and persistent breast cancer (1). Positive wound cultures were obtained in four of the seven infected patients (57 percent), requiring expander removal for infection. Tissue expanders were removed in 11 patients for complications directly related to the expander. Among these, six (55 percent) were receiving adjuvant chemotherapy, and one was a smoker. Diabetes, obesity, other concomitant medical illnesses, and prior mantle irradiation were not associated with expander removal. Premature removal of the tissue expander was required in only 1.8 percent of the patients in this series. Infection was the most common complication necessitating an unplanned surgical procedure to remove the expander. This study demonstrates that the use of tissue expanders in breast reconstruction is reliable, with the vast majority of patients completing the expansion process.     

Eighty-four consecutive breast reconstructions using a textured silicone tissue expander.

Breast reconstruction utilizing smooth-surface silicone tissue expanders is associated with certain problems. Significant capsular contracture may develop around the expander with subsequent expander displacement necessitating repositioning or capsulectomy at the time of expander removal. Infection, pain on expansion, chest-wall compression, and complications related to the remote fill valve also have been reported. A textured-surface silicone expander with an integrated fill valve was developed to address these issues. Eighty-four consecutive breast reconstructions were performed by a single surgeon using textured expanders in 55 patients. Intraexpander pressures were measured during expansion for a group of these patients, and both initial and postinflation pressure readings were quite low (average initial pressure 2.88 mmHg; average postinflation pressure 12.87 mmHg). Eighty-one of the reconstructions have been completed without any expander losses and with minimal complications. Tissue expander volume averaged 580 cc, and the expansion duration averaged 5.6 months. Various types and configurations of permanent implants were used to complete the reconstructions. Eighty-four percent of our patients' completed reconstructions (including nippleareola reconstruction and opposite breast alteration, when necessary) were accomplished with just two procedures. Seventeen long-term adjustable textured-surface expander/implants with anatomic breast shape are still in place, all after only one operation. The inframmary fold has generally been established passively by the expansion process alone. Textured-surface silicone expanders have stayed where positioned, have expanded easily with minimal patient pain, and have created a noncontractile soft-tissue cover for the final implant. The textured expander with an integrated fill valve has simplified breast reconstruction by helping to limit the problems encountered with smooth silicone expanders. The resulting reconstructions have remained soft with a very acceptable aesthetic appearance. The patient office and hospital charts and photographs of this consecutive series were notarized and submitted to the Editor of this Journal, whose biostatistician randomly selected the cases illustrated.     

Tissue expansion using osmotically active hydrogel systems for direct closure of the donor defect of the radial forearm flap.

Although widely used, the radial forearm flap has been criticized for the poor quality of its donor site. Attempts to avoid donor-site problems have concentrated on the elaboration of the split-thickness and full-thickness skin graft methods of reconstruction. Skin grafts frequently fail over the flexor carpi radialis tendon, leading to chronic skin breakdown or, at best, tendon adhesion. Tissue expansion appears to be a good alternative that allows the use of local tissues to ultimately improve the forearm donor-site appearance. To avoid the disadvantages of traditional silicone balloon expanders (such as pressure peaks, infection, the valve at a distance from the expander, postoperative fillings), an osmotically active system was used. In an 18-month prospective study, 10 osmotically active hydrogel tissue expanders were placed on the forearms of 10 patients. The radial forearm flap was performed for intraoral reconstruction after surgical resection of oral cavity malignancies. The study showed that, in nine out of 10 patients, the expanded skin achieved was sufficient to cover the donor site after raising the forearm flap. Additionally, the expansion-related swelling pressure was well tolerated by the patients, the cosmetic results were very satisfactory, and the incidence of complications was very low. By using osmotically active hydrogel tissue expanders, there is no postoperative filling and no risk of complications arising from defective balloon expanders, filling valves, or missing ports.     

Breast reconstruction using tissue expanders and implants in Hodgkin's patients with prior mantle irradiation.

Women treated for Hodgkin's disease with mantle irradiation have an increased risk for developing breast cancer. Typically, breast malignancy in Hodgkin's patients presents bilaterally in a younger age group. Skin flap ischemia, poor skin expansion, implant extrusion, capsular contracture, and poor cosmesis are common sequelae of tissue expander/implant breast reconstruction after breast irradiation for failed breast conservation therapy. This has led most surgeons to favor autologous tissue reconstruction in this setting. This study was performed to determine the efficacy of tissue expander/implant breast reconstruction in breast cancer patients who have been treated with prior mantle irradiation for Hodgkin's disease. A retrospective analysis of all breast cancer patients with a history of Hodgkin's disease and mantle irradiation treated with mastectomy and tissue expander/implant reconstruction between 1992 and 1999 was performed. There were seven patients, with a mean age of 35 years (range, 28 to 42 years). The average interval between mantle irradiation and breast cancer diagnosis was 16 years (range, 12 to 23 years). All patients underwent two-stage reconstruction. Textured surface tissue expanders were placed in a complete submuscular position at the time of mastectomy. Expansion was initiated 2 weeks after insertion and continued on a weekly basis until completion. Expanders were replaced with textured surface saline-filled implants as a second stage. Patients were evaluated for skin flap ischemia, infection, quality of skin expansion, implant extrusion, capsular contracture, rippling, symmetry, and final aesthetic outcome. Breast cancer was bilateral in five patients and unilateral in two. Two patients did not undergo simultaneous bilateral breast reconstruction because of metachronous cancer development. One of the patients had an initial transverse rectus abdominis muscle flap breast reconstruction, followed by a tissue expander/implant reconstruction of the opposite breast. The average follow-up was 3 years. Complications were limited to one case of cellulitis after implant placement that resolved with intravenous antibiotics. There were no cases of skin flap ischemia, poor skin expansion, or implant extrusion. Overall patient satisfaction was high and revisions were not requested or required. Symmetry was best achieved with bilateral implants. This study demonstrates the efficacy of tissue expander/implant breast reconstruction in patients treated with prior mantle irradiation. In this series, tissue expansion was reliable with low morbidity. Second-stage placement of permanent implants yielded good aesthetic results without significant capsular contracture. Mantle irradiation did not appear to compromise the prosthetic breast reconstruction. Tissue expander/implant breast reconstruction should remain a viable option in this category of irradiated patients.     

The role of tissue expansion in the treatment of atypical facial clefting

Tissue expansion can be a valuable tool in the reconstruction of soft-tissue defects in craniofacial clefts. To our knowledge, there have been no reports in the literature of the use of tissue expanders to help solve this problem. We report the case of a child with an atypical Tessier no. 3 craniofacial cleft who had a forehead tissue expander placed, inflated, and thus used to provide sufficient local facial skin for repair of the soft-tissue defect.     

Immediate breast reconstruction with tissue expansion

Between October of 1983 and June of 1985, 31 patients underwent primary breast reconstruction with tissue expansion. Tissue expansion was utilized for breast reconstruction when the remaining muscle and skin following modified radical mastectomy was insufficient to accommodate a prosthesis that matched in size and shape the opposite breast. All expanders were placed beneath an investing muscular pocket created by elevating the pectoralis major and serratus anterior. Postoperative expansion began within 1 week, and the breast was expanded to double the volume of the opposite breast. Twenty-two patients have completed their reconstruction with a mean follow-up in 7 months. There were nine complications, including five deflations and four infections. All patients have remained Baker I or Baker II. Creating ptosis to match the breast was accomplished by placing the expander below the rectus fascia and superiorly advancing this expanded tissue at the time of prosthesis placement. Primary breast reconstruction with tissue expansion following modified radical mastectomy is safe, simple, and produces a breast with excellent shape, size, texture, and patient satisfaction.     

Delayed-immediate breast reconstruction

In patients with early-stage breast cancer who are scheduled to undergo mastectomy and desire breast reconstruction, the optimal timing of reconstruction depends on whether postmastectomy radiation therapy will be needed. Immediate reconstruction offers the best aesthetic outcomes if postmastectomy radiation therapy is not needed, but if postmastectomy radiation therapy is required, delayed reconstruction is preferable to avoid potential aesthetic and radiation-delivery problems. Unfortunately, the need for postmastectomy radiation therapy cannot be reliably determined until review of the permanent tissue sections. The authors recently implemented a two-stage approach, delayed-immediate breast reconstruction, to optimize reconstruction in patients at risk for requiring postmastectomy radiation therapy when the need for postmastectomy radiation therapy is not known at the time of mastectomy. Stage 1 consists of skin-sparing mastectomy with insertion of a completely filled textured saline tissue expander. After review of permanent sections, patients who did not require post-mastectomy radiation therapy underwent immediate reconstruction (stage 2) and patients who required postmastectomy radiation therapy completed postmastectomy radiation therapy and then underwent standard delayed reconstruction. In this study, the feasibility and outcomes of this approach were reviewed. Fourteen patients were treated with delayed-immediate reconstruction between May of 2002 and June of 2003. Twelve patients had unilateral reconstruction and two patients had bilateral reconstruction, for a total of 16 treated breasts. All patients completed stage 1. Tissue expanders were inserted subpectorally in 15 breasts and subcutaneously in one breast. The mean intraoperative expander fill volume was 475 cc (range, 250 to 750 cc). Three patients required postmastectomy radiation therapy and underwent delayed reconstruction. Eleven patients did not require postmastectomy radiation therapy. Nine patients had 11 breast reconstructions (stage 2), six with free transverse rectus abdominis musculocutaneous (TRAM) flaps, one with a superior gluteal artery perforator flap, and four with a latissimus dorsi flap plus an implant. The median interval between stages was 13 days (range, 11 to 22 days). Two patients who did not require postmastectomy radiation therapy have not yet had stage 2 reconstruction, one because she wished to delay reconstruction and the other because she required additional tissue expansion before permanent implant placement. Six complications occurred. The stage 1 complications involved two cases of mastectomy skin necrosis in patients who required post-mastectomy radiation therapy; one patient required removal of the subcutaneously placed expander before postmastectomy radiation therapy and the other patient had a subpectorally placed expander that only required local wound care. The stage 2 complications were a recipient-site seroma in a patient with a latissimus dorsi flap, a recipient-site hematoma in the patient with the superior gluteal artery perforator flap, and two arterial thromboses in patients with TRAM flaps. Both TRAM flaps were salvaged. Delayed-immediate reconstruction is technically feasible and safe in patients with early-stage breast cancer who may require postmastectomy radiation therapy. With this approach, patients who do not require postmastectomy radiation therapy can achieve aesthetic outcomes essentially the same as those with immediate reconstruction, and patients who require postmastectomy radiation therapy can avoid the aesthetic and radiation-delivery problems that can occur after an immediate breast reconstruction.     

Continuous versus intraoperative expansion in the pig model.

Continuous tissue expansion utilizing a continuous infusion device that maintains a constant expander pressure was previously demonstrated to be feasible and successful in obtaining rapid tissue expansion in a canine model. Intraoperative tissue expansion has been described and has gained some clinical acceptance as a method to gain rapid expansion. We compared the efficacy of continuous tissue expansion versus intraoperative tissue expansion in a piglet model. After completing a pilot study, continuous tissue expansion was performed in six pigs (14.5 to 20 kg) on one flank over a 3-day period utilizing an improved prototype device; at the termination of continuous tissue expansion, intraoperative tissue expansion was performed on the opposite flank. There were no complications or continuous tissue expansion device malfunctions. Intraoperative tissue expansion gave a true gain in area of 7.4 percent, while continuous tissue expansion produced a 22 percent gain (p < 0.02). When the effects of both recruitment and expansion were added, continuous tissue expansion gave a dividend of 286 percent versus 192 percent for intraoperative tissue expansion (p < 0.01). Biomechanically, intraoperative tissue expansion skin showed few differences from unexpanded skin, while continuous tissue expansion skin showed a significant increase in stress relaxation (47.78 versus 38.74) and decrease in breaking strength. Histologic analysis revealed some epidermal hyperplasia and inflammation surrounding the continuous tissue expansion expander and some vascular congestion over the intraoperative tissue expansion expander. We conclude that continuous tissue expansion is superior to intraoperative tissue expansion and that the prototype device may be useful clinically.     

Enhancement of Tissue Expansion by Calcium Channel Blocker: A preliminary study

BACKGROUND: Reconstruction of the defects after surgical resection of tumors is one of the important issues in surgical oncology. It is essential that the defect should be covered with a tissue quite similar to the original one and is best achieved by harvesting tissue from an area adjacent to the defect. Tissue expansion is one of the most frequently used reconstructive techniques. A number of studies evaluated blood circulation, capsule formation, tissue tolerance, histomorphological changes and complications of expander placement. However, only a few attempted to enhance tissue expansion. This study we aimed to evaluate verapamil, a calcium channel blocker, to enhance tissue expansion. MATERIAL AND METHOD: Twelve New Zealand rabbits weighing between 900 gm and 1200 gm were assigned into study and control groups. High volume expanders (100, 200 or 300 cc) were placed into the subcutaneous tissue. Rabbits in the study group received verapamil. Expanders in the control group were inflated every three days to achieve same pressure as the study group. The size of the flaps was assessed by applying pressure on tip of the flap to demonstrate the contraction. Histopathological examinations were performed. RESULTS: By administering liquid earlier and more quickly less flap retraction was observed in the study group. In the control group expanders were exposed in two rabbits while no complication occurred in the study group. Following extraction of the expanders, the flaps were elevated and less retraction was observed in the study group compared to controls. CONCLUSION: Verapamil is safe when used topically and provides less retracted flaps. It can be suggested that verapamil acts on the myofibroblasts in the capsule around tissue expanders and thus increases efficiency of the expanders.     

Patient-activated controlled expansion for breast reconstruction with controlled carbon dioxide inflation: a feasibility study

This feasibility study represents the first report of a new carbon dioxide-based tissue expander designed to allow gradual controlled expansion and to eliminate the need for percutaneous injections. Seven patients underwent implantation with a total of 10 (three bilateral) tissue expanders. After intraoperative filling by the surgeon and wound healing, small doses of carbon dioxide were administered on a daily basis by the patient by means of a hand-held dosage controller leading to gradual, incremental expansion. Rapid expansion during the active dosing phase and flexibility to meet individual patient needs during expansion were demonstrated with all subjects. These patients achieved full expansion in an average of 15 days. All seven patients were able to use the device safely and with ease at home, leading to successful tissue expansion and permanent breast reconstruction. CLINICAL QUESTION/LEVEL OF EVIDENCE: Therapeutic, IV.     

Magna-Site tissue expander: an innovation for injection site location

The Magna-Site tissue expander simplifies the use of tissue expanders by facilitating the location of the injection port, thereby reducing the risks associated with faulty injection placement in the past. The injection port is smooth except for the innocuous palpation bumps, drastically reducing the problems of erosion at the injection port site encountered in the past. No drawbacks were encountered with the use of this expander relative to the use of other currently marketed expanders. The new product is available at a cost similar to expanders currently available. It is felt by the authors that this expander represents the next logical step in the evolution of this technology. Just as Dr. Cohen thought, "It will be exciting to see what new devices are created to further enhance the concept of tissue expansion."     

Irradiation after immediate tissue expander/implant breast reconstruction: outcomes, complications, aesthetic results, and satisfaction among 156 patients

Chest wall irradiation is becoming increasingly common for mastectomy patients who have opted for immediate breast reconstruction with tissue expanders and implants. The optimal approach for such patients has not yet been defined. This study assesses the outcomes of a reconstruction protocol for patients who require irradiation after tissue expander/implant reconstruction. The charts of all patients who underwent immediate tissue expander/implant reconstruction at Memorial Sloan-Kettering Cancer Center between January of 1995 and June of 2001 and who had not previously undergone irradiation were retrospectively reviewed. A subgroup of patients who required chest wall irradiation after mastectomy and reconstruction was identified. Those patients were treated according to the following treatment algorithm: (1) reconstruction with tissue expander placement at the time of mastectomy , (2) tissue expansion during postoperative chemotherapy, (3) exchange of the tissue expander for a permanent implant approximately 4 weeks after the completion of chemotherapy, and (4) chest wall irradiation beginning 4 weeks after the exchange. All irradiated patients with at least 1 year of follow-up monitoring after the completion of radiotherapy were evaluated with respect to aesthetic outcomes, capsular contracture, and patient satisfaction. A control group of nonirradiated patients was randomly selected from the cohort of patients treated during the study period. During the 5-year study period, a total of 687 patients underwent immediate reconstruction with tissue expanders. Eighty-one patients underwent postoperative irradiation after placement of the final implant. A total of 68 patients who received postoperative chest wall irradiation underwent at least 1 year of follow-up monitoring after the completion of radiotherapy, with a mean follow-up period of 34 months. Seventy-five nonirradiated patients were evaluated as a control group. Overall, 68 percent of the irradiated patients developed capsular contracture, compared with 40 percent in the nonirradiated group (p = 0.025). Eighty percent of the irradiated patients demonstrated acceptable (good to excellent) aesthetic results, compared with 88 percent in the nonirradiated group (p = not significant). Sixty-seven percent of the irradiated patients were satisfied with their reconstructions, compared with 88 percent of the nonirradiated patients (p = 0.004). Seventy-two percent of the irradiated patients stated that they would choose the same form of reconstruction again, compared with 85 percent of the nonirradiated patients. The results of this study suggest that tissue expander/implant reconstruction is an acceptable surgical option even when followed by postoperative radiotherapy and should be considered in the reconstruction algorithm for all patients, particularly those who may not be candidates for autogenous reconstruction.     

Treatment of burn alopecia with tissue expanders in children

During the past 18 months, 60 tissue expanders were utilized in the reconstruction of 42 children with burn alopecia of the scalp not amenable to a single excision and primary closure at the Shriners Burns Institute in Galveston, Texas. The children were grouped according to the degree of alopecia. All patients with defects of 15 percent or less of the total hair-bearing scalp were able to obtain complete closure of their defects with two operations, i.e., one to place the expander and the second to remove the expander and advance the flaps. Some patients with defects up to 40 percent were closed with serial expansion. Patients with even larger defects had a significant reduction in the percentage of alopecia and benefited from re-creation of anterior hairlines. We have encountered a postoperative complication rate of 10 percent. When compared to previous methods of treating burn alopecia, tissue expansion allows a more rapid closure, fewer operations and coincident anesthetics, and decreased total length of hospitalization.     

Correction of congenital microtia using the tissue expander

We attempted auricular reconstruction using Radovan-type inflatable silicone expanders in six children and one adult, with the complete hypoplastic, the conchal remnant, and constricted type of microtia. Ear frameworks, including the helix, anthelix, concha, and tragus, were prepared using autologous rib cartilage. Based on the surface area of the normal adult auricle, the silicone expander was tentatively shaped and sized into a rotated semiellipse and expanded with 70 cc saline. Auricular reconstruction on the framework was completed at the time of insertion in four of the seven patients, requiring no elevation of the ear. The reconstructed auricle was satisfactory in both color and texture and had nearly normal sensation. Mild complications were noted in three of the seven patients. However, no resorption of the inserted rib cartilage has been observed 14 months to 2 years and 5 months after the operation. Slight shrinkage of the expanded skin was noted in each patient.     

The role of tissue expanders in an anophthalmic animal model

A study of orbital bony expansion using a custom tissue expander was performed in the anophthalmic cat model. Twelve 6-week-old kittens underwent right unilateral enucleations. Six kittens had immediate insertion of a tissue expander into the orbit. The remaining six served as controls. Every 2 weeks 0.5 cc saline was injected into the expander to a maximum of 5 cc. External horizontal and vertical orbital dimensions were obtained by palpation technique weekly. All animals had preoperative and study conclusion head CT scans with three-dimensional reconstructions performed. Dry skull preparations were done at the study conclusion at 24 weeks. Results demonstrated that tissue expanders were successful in maintaining normal orbital growth and size relative to the contralateral control orbit. The animals with enucleation only had an average difference in vertical and horizontal orbital measurements of -27 and -13 percent when compared with the contralateral normal orbit. In contrast, the enucleation and tissue-expansion animals had vertical and horizontal measurements of +4 and +2 percent (p less than 0.05) when compared with the contralateral orbit. Head CT scans with three-dimensional reconstructions demonstrated normal orbital geometry and volume for the animals with tissue expanders, whereas animals with enucleation only had small hypoplastic orbits. In conclusion, orbital tissue expanders offer a promising new technique in the treatment of anophthalmos.     

Long-term effects of tissue expansion on cranial and skeletal bone development in neonatal miniature swine: clinical findings and histomorphometric correlates

Progressive tissue expansion induces significant gross, histologic, and bony changes in skulls and long bones of neonatal miniature swine. These bony changes consist of erosion underlying tissue expanders, with bony lipping and bone deposition at the periphery of the expander. Cranial suture lines underneath expanders appear effaced and convoluted. Serial CT scans reveal decreased bone thickness and volume (p less than 0.02) but identical bone density (p = 0.60) beneath expanders. Increased bone volume and thickness occur at the periphery of expanders (p less than 0.02). Bone density (CT number) is unaffected by tissue expansion in both cranial and long bones. These findings have histomorphometric correlates: Osteoclastic bone resorption occurs underneath expanders with periosteal reaction at the periphery of expanders. Cranial sutures are similarly affected, but no cranial synostosis results. No changes to the inner table of the skull or stigmata of increased intracranial pressure were observed either in CT scans or in behavioral changes in long-term animals. The pathophysiology of bony changes is a remodeling effect, not one of simple pressure deformation. Increased bone resorption and complete inhibition of bone formation occur until the pressure is removed. Cranial bone is significantly more affected than long bone. After removal of the expanders, reparative bone remodeling begins within 5 days and nearly complete healing of the cranial defects occurs within 2 months (p less than 0.02). No plagiocephaly results despite early coronal suture changes. On the basis of this study, we conclude that tissue expansion causes significant but reversible effects, readily monitored by high-resolution CT scans, on neonatal and infant cranial and long bones.     

Accelerating tissue expansion by application of topical papaverine cream

The rate of tissue expansion can be accelerated by papaverine through a special delivery system, according to an early report. Because the delivery system was complex and inconvenient, another means of administrating papaverine was tested to observe the rate of tissue expansion. In this study, 24 miniature pigs were divided equally into three groups. Four 150-ml silicone expanders were implanted into each pig in groups A and C. Four modified rectangular silicone expanders were also implanted into each animal in group B. During the expansion process, 1 g of 2% hydrochloride papaverine cream was applied topically onto the surface of each pig's expanding skin in group A two times daily, and hydrochloride papaverine solution was injected into the outer shell of each modified expander in group B weekly. Group C acted as the control group. The mean sum of the first four times of saline water volume that was injected into the expanders was 142.42 +/- 5.6 ml in group A, 128.72+/-4.8 ml in group B, and 106.38+/-3.28 in group C. There were statistical differences among the three groups. The mean sum of volume saline water that was injected into hind expanders was 137.51 +/- 5.1 ml in group A, 120.35 +/- 3.6 ml in group B, and 102.63 +/- 4.76 ml in group C, and there was a statistical difference among the three groups as well. There was no statistically significant difference in the thickness of fibrous capsules among the three groups. This study shows that the rate of tissue expansion can be accelerated by topical application of papaverine cream, and the rate is better than the rate of tissue expansion induced by the special drug delivery system.     

Enhancement of tissue expansion by anticontractile agents

To evaluate the effect of anticontractile agents on the rate of tissue expansion, guinea pig back skin was expanded while being treated with various anticontractile agents. Expansion was carried out using standard percutaneous inflatable skin expanders modified by the addition of a catheter to deliver the anticontractile agents papaverine or cytochalasin D. Expansion proceeded for 25 days with one or other of the substances being infused through the catheter; saline was used in a separate control group. Measurements of the rate and extent of expansion showed that there was a statistically significant increase in these parameters for the experimental groups as compared with saline controls. Histologic examination of the expanded tissue suggests that the cellular basis for this phenomenon may involve the relaxation or inactivation of contractile fibroblasts in the fibrous capsule surrounding the expander.     

Alterations in skin properties during rapid and slow tissue expansion for breast reconstruction.

This study comprises 23 women who had had mastectomies because of breast cancer. They were randomly divided into two groups when they were admitted for breast reconstruction by tissue expansion. The first group was expanded rapidly, i.e., every day, and the other group was expanded slowly, i.e., every week. There were no other differences in the treatment between the two groups. Three months after completion of expansion, the expander was replaced by a permanent prosthesis. The follow-up time was up to 6 months after the second operation. Three different parameters--distensibility, elasticity, and hysteresis--were measured noninvasively on the breast skin and at a control site on several occasions throughout the treatment. During the treatment period there were no differences in skin properties between rapidly and slowly expanded patients. Of the three parameters, distensibility showed the most prominent changes: decreasing during the expansion period, increasing after the expander had been replaced by a permanent prosthesis, and decreasing during the following 6 months. Elasticity did not change significantly, except decreasing after insertion of the permanent prosthesis, and the hysteresis increased at the same time. These findings indicate that tissue expansion alters breast skin only to a small extent and that the mechanical resistance sometimes encountered during tissue expansion is due to deeper structures such as underlying muscles or capsule formation.